Greasing for power in electric motors

Electric motors are omnipresent, with millions in use worldwide powering a vast array of industrial processes. However, their operation is very energy intensive, amounting to 40 per cent of total global energy consumption! We discuss how one key technique to lessen their energy consumption is to use a high performance grease for lubricating electric motor bearings.


Electric motors are everywhere. There are millions in use worldwide, powering a vast array of industrial processes. Their operation is, however, very energy intensive: electric motors account for approximately 40 per cent of total global energy consumption.

By 2024, the global industrial electric motor market is expected to reach US$175.5 billion in sales. Hence it is clear that any steps to reduce energy consumption of electric motors can help businesses – by improving their profitability, protecting their bottom line, and reducing their carbon emissions.

One important, but sometimes overlooked, technique for curbing power use is to employ a high performance grease for lubricating electric motor bearings. By reducing bearing torque, a grease can decrease a motor’s operating power intake. A high performance grease can also:

  • Reduce friction and prevent wear
  • Protect bearings against corrosion
  • Act as a seal to prevent entry of contaminants

Taken together, these benefits can help reduce costly maintenance, increase bearing life, and cut energy bills.

Issues and complications

All greases deteriorate over time, even under moderate operating conditions. The principal causes are oxidation, excessive oil bleeding, and mechanical working:

  • Oxidation eventually increases the oil viscosity and hardens the thickener.
  • While some oil bleeding is desirable, too much reduces the ability of the grease to maintain an effective lubrication film.
  • Mechanical working, or shearing, may change grease properties, such as consistency, making the grease less suited to the application

Deterioration often ends in hard, dry deposits that can neither lubricate bearings nor protect them against contaminants. It is therefore important to know what to look for and select a high performance grease when selecting a grease for use in electric motors.

What to look for in a grease

A grease comprises three components: a base oil, a thickener, and an additives package that adds desirable performance characteristics such as protection against oxidation, corrosion and wear. This combination can be precisely formulated to meet the demands of specific applications.

Those designed for use in electric motors, for example, need to be able to function at high temperatures for prolonged periods without compromising on equipment protection. Ideally, the grease will also possess:

  • An appropriate oil viscosity to help maintain optimum protection and component life.
  • A consistency that does not affect ‘pumpability’ – the ability to distribute a grease to the areas needing lubrication.
  • Oxidation resistance to extend the life of the grease and the life of bearings running at high speeds and temperatures.
  • Structural stability to ensure the oil will not separate from the thickener when running hot.
  • Good shear stability to prevent grease softening and leaking from bearings.


ExxonMobil developed Mobil SHC PolyrexTm EM synthetic greases, which were specifically formulated for use in electric motors. Mobil SHC PolyrexTm 102 EM is recommended for most conventional electric motor ball and roller bearings, while Mobil SHC PolyrexTm 103 EM is formulated for applications such as vertically mounted bearings, or very large motors where a stiffer grease consistency is recommended by the OEM. Testing has shown that both grades have the ability to deliver excellent equipment protection, while Mobil SHC PolyrexTm 102 EM has been shown to increase the mechanical efficiency of electric motors.

People often underestimate the benefits offered by high performance greases. Although reducing energy consumption is a huge bonus for all manufacturers, high performance greases also provide lower maintenance costs and longer equipment life, thereby affording notable savings and productivity benefits.

So it’s worth remembering that not all greases are created equal.

For electric motors, the greatest advantages are available from greases formulated with high performance synthetic base stock, thickener, and additive technology that confer a balanced performance tailored for the unique operating conditions of electric motors.

Let us know in the comments below, if you have any further questions on picking the right grease for your equipment. Otherwise, hit ‘Like’ on the toolbar to the right if you found this article useful!

  • Excelente información hemos aplicado a unos Mobil SHC Polyrex 103 EM, en rodamientos de sopladores, equipos donde existen temperaturas elevadas y alta humedad. 

  • Muy buena información sobre las grasas de alto rendimiento para estos motores eléctricos,los ahorros de energía y menos repuestos en los rodamientos.

  • Unfortunately only in certain size have nipple for relubrication of the bearing motor, so it relies on lubrication that builds in  the bearing motor.

  • Very informative. The product range that Mobil have is best of the class and apart from the competition. Saving millions of electric motors from bearing failures with reduced regreasing intervals. Every application demands a different treatment and that is taken care by Mobil products .whether vertically mounted or horizontal , No matters Mobil has a solution with expertise.

  • Definitivamente Mobil esta a la vanguardia en tecnología y calidad de sus productos, en comparativa con productos de otras marcas es muy notable sus amplia ventaja, sin dudar en un futuro donde la motorización eléctrica va a la alza Mobil seguirá posicionado como la mejor marca con los mejores productos  para las aplicaciones requeridas.